JP6441140B2 - Method for producing titanium oxide fine powder using spent catalyst and method for producing exhaust gas treatment catalyst using the powder - Google Patents

Description

  The present invention relates to a method for producing an exhaust gas treatment catalyst using a spent catalyst and an exhaust gas treatment catalyst.

Conventionally, stationary sources such as power plants, pollutants and country NO _x exhausted from mobile sources such as an automobile, selective reduction the NO _x catalyst (hereinafter, referred to as SCR catalyst) has been treated with a honeycomb catalyst as .

  In the case of fixed sources such as power plants, coal, heavy oil, wood, etc. are used as fuel. For example, in the case of coal, V, Ni, Fe, Hg, As, Si, Ca, Mg are used as combustion exhaust gas. , S component, ash, etc. are included, and these are deposited and deposited on the exhaust gas treatment catalyst, and it is known that the catalyst performance is physically and chemically deteriorated. Therefore, when the performance deterioration reaches a certain level, it is operated with a new exhaust gas treatment catalyst.

  Here, if the used catalyst taken out is discarded as it is, environmental problems may be caused, and the used catalyst contains a lot of useful components such as titanium oxide, Mo, W, V, and active metal components. Therefore, it is being considered to recycle and reuse. JP 2005-185928 A (Patent Document 1), JP 2011-251245 A (Patent Document 2)

For example, Japanese Patent Laid-Open No. 2005-185928 (Patent Document 1) describes a denitration performance and SO ₂ oxidation by heat treatment of an exhaust gas treatment catalyst used for combustion exhaust gas of superheavy oil and then washing with an oxalic acid aqueous solution. A method for regenerating a spent exhaust gas treatment catalyst capable of recovering performance is disclosed.

  Japanese Patent Application Laid-Open No. 2011-251245 (Patent Document 2) discloses that a used exhaust gas treatment catalyst is pulverized and refined, a molded body for a substrate is prepared using this, and a new exhaust gas treatment catalyst is separately pulverized. A method for regenerating a used exhaust gas treatment catalyst is disclosed in which this is used as a slurry liquid and the surface of the molded body for a substrate is coated with this slurry liquid.

JP 2005-185928 A JP 2011-251245 A

However, the method described in Patent Document 1 does not always have sufficient recovery of NOx removal performance and SO ₂ oxidation ability, and in addition, treatment of a large amount of washing waste liquid containing impurities such as vanadium and sulfate ions and oxalic acid used in the treatment. There was a problem in economic efficiency.

  Further, in the method of Patent Document 2, the moldability of the molded body using the pulverized spent exhaust gas treatment catalyst is inferior to that of a normal exhaust gas treatment catalyst, and the honeycomb has a large diameter, a thin wall, or a large number of pitches. In some cases, it may be difficult to mold the shaped molded body. In addition, the adhering substances cannot be sufficiently removed in the process of firing and regeneration, and the initial exhaust gas treatment performance and catalyst life compared to ordinary exhaust gas treatment catalysts. Was insufficient.

  The present invention provides a method for producing an exhaust gas treatment catalyst and an exhaust gas treatment catalyst that are excellent in moldability, strength, wear resistance, and the like, and are excellent in exhaust gas treatment catalyst performance, using a used titanium oxide-containing exhaust gas treatment catalyst. It is an issue.

  Therefore, as a result of intensive studies, the present inventors have crushed into titanyl sulfate or metatitanic acid slurry, which is usually used as a raw material, when preparing a titanium oxide-based fine powder used in the preparation process of a conventional exhaust gas treatment catalyst. Mixing and filtering spent titanium oxide-containing exhaust gas treatment catalyst can remove alkali metals and alkaline earth metals such as Na, K, and Ca, which are components that degrade the catalyst, and if this is used as the main raw material, moldability It was found that the obtained exhaust gas treatment catalyst was excellent in strength, abrasion resistance, exhaust gas treatment performance, etc., and completed the present invention.

The method for producing an exhaust gas treatment catalyst according to the present invention comprises:
After pulverizing the spent titanium oxide-containing exhaust gas treatment catalyst to obtain a powder having an average particle size of 0.1 to 15 μm,
Concentration (C _T ) of titanyl sulfate aqueous solution and / or metatitanic acid slurry and spent titanium oxide-containing exhaust gas treatment catalyst powder as TiO _{2 in the} aqueous solution of titanyl sulfate and / or metatitanic acid slurry and used oxidation A mixed slurry is prepared by mixing so that the concentration ratio (C _T ) / (C _RC ) with the concentration (C _RC ) as the solid content of the titanium-containing exhaust gas treatment catalyst is in the range of 0.1 to 9.0. ,
After filtering the mixed slurry, a basic compound is added to neutralize titanyl sulfate and / or metatitanic acid to prepare a titanium oxide gel having a pH in the range of 7 to 12,
The gel is fired and then pulverized to prepare a titanium oxide fine powder,
Mixing the titanium oxide fine powder and the reinforcing material,
The mixture is fired after molding.

The active ingredient precursor compound may be mixed before neutralization with the basic compound, or the active ingredient precursor compound may be mixed together with the reinforcing material.
The active component precursor compound is a compound of at least one element selected from V, W, Mo, Cr, Mn, Fe, Ni, Cu, Ag, Au, Pd, Y, Ce, Nd, In, and Ir. The metal or oxide of the element can be generated.

The exhaust gas treatment catalyst according to the present invention is obtained by the above method,
(i) a titanium oxide fine powder and (ii) a reinforcing material, (i) a content of titanium oxide fine powder is in the range of 60 to 97% by weight, and (ii) a reinforcing material content is 3 It is characterized by being in the range of ˜15% by weight.

Furthermore, it is preferable that (iii) the active ingredient is contained, and the content of the (iii) active ingredient is in the range of 0.001 to 15% by weight as an oxide.
The content of the titanium oxide-based oxide (or component) derived from the spent titanium oxide-containing exhaust gas treatment catalyst in the (i) titanium oxide-based fine powder is preferably in the range of 8.5 to 90% by weight.

Furthermore, it is preferable that a filler is included and the content of the filler is in the range of 0.5 to 15% by weight.
The exhaust gas treatment catalyst is a honeycomb molded body, the honeycomb has an outer diameter in the range of 30 to 400 mm, a length in the range of 3 to 1500 mm, a pitch in the range of 6 to 500 cpsi, and a wall thickness of 0. It is preferable that it exists in the range of 0.1-1.9 mm.

The active component is a metal or metal oxide of at least one element selected from V, W, Mo, Cr, Mn, Fe, Ni, Cu, Ag, Au, Pd, Y, Ce, Nd, In, and Ir It is preferable that
The content of the active ingredient is preferably in the range of 0.001 to 15% by weight as an oxide.

  According to the present invention, it is possible to provide a method for producing an exhaust gas treatment catalyst and an exhaust gas treatment catalyst that are excellent in moldability, strength, abrasion resistance, and exhaust gas treatment catalyst performance, and in addition, are excellent in economy.

First, a method for producing an exhaust gas treatment catalyst according to the present invention will be described.
[Method for producing exhaust gas treatment catalyst]
In the method for producing an exhaust gas treatment catalyst according to the present invention, a used titanium oxide-containing exhaust gas treatment catalyst is pulverized to obtain a powder having an average particle size of 0.1 to 15 μm (step (a)).

Step (a)
The spent titanium oxide-containing exhaust gas treatment catalyst is pulverized.
As the spent titanium oxide-containing exhaust gas treatment catalyst, the one used mainly for the selective reduction treatment of pollutants, particularly NO _x gas, emitted from fixed sources such as the above-mentioned power plants and mobile sources such as automobiles is used. be able to.

The used titanium oxide-containing exhaust gas treatment catalyst preferably contains 50% by weight or more of titanium oxide as TiO ₂ except for ash and the like described later.
As the spent titanium oxide-containing exhaust gas treatment catalyst, a honeycomb-like one used for treatment of exhaust gas generated at a fixed generation source such as a power plant using coal, heavy oil, wood or the like as fuel is preferably used. .

  In particular, when coal is used as fuel, combustion exhaust gas contains V, Ni, Fe, Hg, As, Si, Ca, Mg, Na, K, S component, ash, etc., and these are used titanium oxide. Although deposited and deposited on the contained exhaust gas treatment catalyst, according to the production method of the present invention, these components contained in the finally obtained exhaust gas treatment catalyst can be selectively reduced or removed.

  A method for pulverizing the used titanium oxide-containing exhaust gas treatment catalyst is not particularly limited as long as it can be pulverized to a desired size, and a conventionally known method can be employed. For example, it can be pulverized using an atomizer, a hensil mixer, a pulverizer, a yary pulverizer, or the like.

  The size of the pulverized spent titanium oxide-containing exhaust gas treatment catalyst is 0 as the average particle size in terms of energy required for pulverization, equipment costs, recovery rate in the pulverization process, filterability and removal of impurities inside the particles. It is preferably in the range of 1 to 15 μm, more preferably 0.5 to 10.0 μm.

  If the average particle size of the pulverized spent titanium oxide-containing exhaust gas treatment catalyst is less than the lower limit of the above range, the energy required for pulverization, the cost of equipment, etc. may increase and the recovery rate in the pulverization process may decrease, and the slurry may be filtered. If the average particle size is too large, the filterability is improved, but the impurities inside the particles of the pulverized used titanium oxide-containing exhaust gas treatment catalyst cannot be removed. For this reason, the cleaning effect may be insufficient.

  In the present invention, the average particle size of the pulverized spent titanium oxide-containing exhaust gas treatment catalyst and the titanium oxide fine powder in the step (h) described later is determined by a laser diffraction scattering type particle size distribution measuring apparatus (manufactured by Horiba: LA-300). ) To measure.

Next, the titanyl sulfate aqueous solution and / or metatitanic acid slurry and the pulverized used titanium oxide-containing exhaust gas treatment catalyst were pulverized with the concentration (C _T ) of the aqueous titanyl sulfate and / or metatitanic acid slurry as TiO ₂ . Mixing slurry so that concentration ratio (C _T ) / (C _RC ) with concentration (C _RC ) as solid content of spent titanium oxide-containing exhaust gas treatment catalyst is in the range of 0.1 to 9.0 To prepare. (Steps (b) and (c))

Step (b)
The aqueous solution of titanyl sulfate and / or metatitanic acid slurry and the pulverized spent titanium oxide-containing exhaust gas treatment catalyst are mixed to obtain a mixed slurry.
Here, the metatitanic acid slurry is a hydrous titanium oxide slurry obtained by hydrolyzing titanium sulfate.

The concentration (C _T ) of TiO _{2 in the} aqueous titanyl sulfate solution and / or metatitanic acid slurry in the mixed slurry is preferably in the range of 5 to 40% by weight, more preferably 10 to 30% by weight. If the concentration (C _T ) in the mixed slurry is low, the economy is reduced, and if the concentration (C _T ) in the mixed slurry is too high, the viscosity of the slurry in step (b) and step (d) is low. It may become high and stirring may become difficult.

  When the pulverized spent titanium oxide-containing exhaust gas treatment catalyst is dispersed in titanyl sulfate and / or metatitanic acid, the pH becomes acidic, and in particular, a salt mainly dissolves in the alkali component and dissolves. The sulfur content becomes sulfate ions. These are removed in the filtration / dehydration step. In addition, a titanium oxide gel is produced from titanyl sulfate and / or metatitanic acid by neutralization (alkaline) by addition of a basic compound described later. Since this gel is produced so as to cover the pulverized spent titanium oxide-containing exhaust gas treatment catalyst, compared with the case of mixing the pulverized spent titanium oxide-containing exhaust gas treatment catalyst after preparing the gel in advance, the exhaust gas A processing catalyst having high moldability and excellent strength can be obtained.

Moreover, it is preferable that the used titanium oxide containing exhaust gas treatment catalyst in the mixed slurry is contained in a concentration (C _RC ) as a solid content of 3 to 55% by weight, more preferably 9 to 25% by weight.

If the concentration (C _RC ) is small, it is not efficient in reusing the used titanium oxide-containing exhaust gas treatment catalyst. If the concentration (C _RC ) is too large, the viscosity of the mixed slurry becomes high and stirring may become difficult.

At this time, the concentration (C _T) and the concentration (C _RC) and the concentration ratio of _{(C T) / (C RC} ) is 0.1 to 9.0, more in the range of 1.0 to 5.0 Preferably there is.
If the concentration ratio (C _T ) / (C _RC ) is too low, the impurities in the pulverized spent titanium oxide-containing exhaust gas treatment catalyst may be insufficiently removed and the moldability may be deteriorated. In some cases, the NOx removal performance of the exhaust gas treatment catalyst obtained is insufficient. Even if the concentration ratio (C _T ) / (C _RC ) is too high, the amount of used titanium oxide-containing exhaust gas treatment catalyst is small, so it is efficient in terms of reusing the used titanium oxide-containing exhaust gas treatment catalyst. is not.

The total solid concentration of the mixed slurry is preferably 8 to 60% by weight, more preferably 19 to 39% by weight.
When the total solid content concentration of the mixed slurry is low, the filtrate in the step (c) increases, and it is necessary to process a large amount of the filtrate with a low impurity concentration, so that the processing efficiency and economy may be lowered. If the total solid concentration of the mixed slurry is too high, the viscosity of the mixed slurry increases, which may hinder stirring and filtration, and may make it difficult to perform subsequent steps. In addition, when the total solid content concentration of a mixing slurry is too high, dilution water can also be added as needed.

  Moreover, normally, the pH of the mixed slurry is in the range of 0.5 to 4, and more preferably in the range of 1.0 to 3.0. When the pH of the mixed slurry is less than 0.5, the removal rate of impurities such as alkali and alkaline earth metal when filtered in the later-described step (c) is not further increased, and in the step (d) It is not economical because the amount of the basic compound used for the sum increases.

When the pH of the mixed slurry exceeds 4, removal of impurities such as alkali and alkaline earth metal may be insufficient.
In addition, when the pH of the mixed slurry is not in the above range, an acid or alkali can be added to adjust the pH to the above range.

As the acid, a mineral acid such as hydrochloric acid, nitric acid or sulfuric acid, or an organic acid such as oxalic acid can be used. As the alkali, sodium hydroxide, potassium hydroxide, sodium carbonate, NH ₄ OH, or the like can be used.

Moreover, the mixed slurry can be heated as necessary.
The heating condition is not particularly limited as long as impurities such as Ca, K, and Na can be efficiently removed by filtration in the next step (c), but a range of approximately 40 to 60 ° C. is preferable. However, stirring is preferable.
By heating the mixed slurry, the neutralization reaction with impurities such as Ca, K, and Na is promoted, and the impurities can be efficiently removed by becoming a soluble salt.

Step (c)
The mixed slurry thus prepared is filtered and dehydrated. There is no restriction | limiting in particular as a filtration / dehydration method, A conventionally well-known method is employable.
For example, a vacuum filtration method, a pressure filtration method, a heavy pressure filtration method, a centrifugal separation and the like can be mentioned.

By filtration and dehydration, Ca, K, Na, S (SO ₄ ) and the like, which are causes of deterioration of the catalyst eluted in the filtrate, and ash can be removed, so that an exhaust gas treatment catalyst having excellent activity can be finally obtained.
The solid content of the filtered and dehydrated cake varies to some extent depending on the size of the particles, but is 30% by weight or more, preferably 45 to 55% by weight.
If the solid content concentration of the filtered and dehydrated cake is low, the dehydration is insufficient, many impurities remain, and the performance of the resulting exhaust gas treatment catalyst may be insufficient.
A basic compound is added to the filtered and dehydrated cake to neutralize titanyl sulfate and / or metatitanic acid to prepare a titanium oxide gel having a pH in the range of 7-12. (Process (d))

Step (d)
A basic compound is added to the filtered and dehydrated cake to neutralize titanyl sulfate and / or metatitanic acid to prepare a titanium oxide gel.
As the basic compound, it is sufficient that titanyl sulfate and / or metatitanic acid is converted into a titanium oxide gel by neutralization, and examples thereof include NH ₄ OH, sodium hydroxide, and potassium hydroxide.

In the present invention, NH ₄ OH is preferably used because it does not contain an alkali metal.
The pH of the neutralized titanium oxide gel is preferably in the range of 7 to 12, more preferably 8 to 10.

When the pH of the titanium oxide gel after neutralization is less than 7, a large amount of sulfate ions may remain, and moldability may be insufficient. Moreover, the specific surface area of the raw material after calcination in the step (g) becomes small, and the performance of the obtained exhaust gas treatment catalyst may be insufficient.
If the pH of the neutralized titanium oxide gel exceeds 12, the amount of the basic compound used increases, and the economic efficiency may decrease.

In the present invention, the active ingredient precursor compound (A) can be mixed before adding a basic compound to neutralize titanyl sulfate and / or metatitanic acid.
The active component precursor compound (A) includes at least one element selected from V, W, Mo, Cr, Mn, Fe, Ni, Cu, Ag, Au, Pd, Y, Ce, Nd, In, and Ir. A compound is used.

  Specifically, ammonium metavanadate, vanadyl sulfate, ammonium paratungstate, ammonium metatungstate, tungstic acid, ammonium molybdate, chromium nitrate, chromium acetate, manganese nitrate, manganese acetate, palladium nitrate, iron sulfate, nickel nitrate, Examples thereof include copper nitrate, silver nitrate, yttrium nitrate, cerium nitrate, gold chloride, and iridium chloride.

  The active component precursor compound (A) is preferably used as a solution, and although it varies depending on the type of compound, it is preferably used after being dissolved in water, an alkali such as monoethanolamine, or an acid such as oxalic acid.

The mixing amount of the active component precursor compound (A) is determined in consideration of the content of the active component in the above-described spent titanium oxide-containing exhaust gas treatment catalyst, and as an elemental oxide in the exhaust gas treatment catalyst finally obtained. The content is preferably 0.001 to 15% by weight, and more preferably 0.3 to 12% by weight. When the content of the active component is small, the NO _x removal rate may be insufficient when used as an exhaust gas treatment catalyst, for example, a selective reduction type NO _x catalyst. Even if there is too much content of an active ingredient, the compressive strength and crack resistance of a molded object will become inadequate.

Next, it is preferable to heat and age after neutralization to achieve the predetermined pH range.
At this time, the aging temperature is preferably in the range of 40 to 95 ° C, more preferably 50 to 75 ° C, and the aging time is generally 1 to 24 hours, although it varies depending on the aging temperature.

  When the aging temperature is within the above range, the gel is homogenized, the moldability in the step (k) is improved, cracks of the resulting molded body are suppressed, and an exhaust gas treatment catalyst excellent in strength, wear resistance, etc. is obtained. be able to.

Step (e)
Next, the neutralized titanium oxide gel is washed. Although cleaning is not necessarily performed, there is no particular limitation as long as impurities such as Ca, K, Na, and SO ₄ can be reduced and removed, and a conventionally known method can be employed.

For example, it can be washed by applying water, preferably hot water, after filtering and dehydrating the neutralized titanium oxide gel using the same apparatus as in step (c).
At this time, when dilute ammonia water is used as water, anions such as sulfate ions can be efficiently removed.

Step (f)
The gel obtained in step (e) is dried.
The drying method is not particularly limited as long as the gel can be powdered, and conventionally known methods can be employed.

The drying temperature varies depending on the drying time, but is generally in the range of 70 to 120 ° C.
The powdered gel is fired and then pulverized to prepare titanium oxide fine powder (steps (g) and (h)).

Step (g)
The firing temperature is preferably in the range of 450 to 700 ° C, more preferably 500 to 650 ° C.
If the firing temperature is low, the crystallization of titanium oxide is insufficient, so that kneading in step (i) is difficult, and water separation during pressure molding is likely to occur, and the moldability may be insufficient. .

Even if the calcination temperature is too high, crystallization of titanium oxide proceeds, the specific surface area becomes small, and the exhaust gas treatment catalyst obtained using this may have insufficient performance.
Although the firing time varies depending on the firing temperature, it is generally 1 to 24 hours.

Step (h)
The average particle size of the titanium oxide fine powder obtained by pulverization after firing is preferably in the range of 0.1 to 15 μm, more preferably 0.5 to 5 μm.
It is not preferable to pulverize the titanium oxide fine powder to the lower limit of the range or less because the energy required for the pulverization, the cost of equipment, etc. are increased and the moldability is not further improved. If the average particle size is too large, the moldability in the step (k) is lowered, and the resulting molded product may be cracked, and the strength, wear resistance and the like may be insufficient.

The pulverization method at this time is not particularly limited as long as the average particle diameter falls within the above range, and a conventionally known method can be adopted. For example, the same method and apparatus as in the step (a) can be adopted. .
Thereafter, the titanium oxide fine powder and the reinforcing material are mixed, the mixture is molded, dried and fired (steps (i) to (m)).

Step (i)
A mixture in which the reinforcing material is mixed with the titanium oxide fine powder (hereinafter referred to as a molding composition) is prepared. The content of the titanium oxide fine powder in the composition is preferably 33 to 80% by weight, more preferably 40 to 75% by weight as a solid content. When the content of the titanium oxide fine powder in the molded body composition is small, molding becomes difficult and the catalyst performance, for example, the NO _x removal rate of the selective reduction type NO _x catalyst may be insufficient. .

As the reinforcing material reinforcing material, a fibrous reinforcing material such as glass fiber or ceramic fiber can be used.
When such a reinforcing material is included, generation of cracks due to shrinkage during drying after extrusion molding can be suppressed, and an exhaust gas treatment catalyst having excellent compressive strength and wear resistance can be prepared.

The content of the reinforcing material in the molded body composition is preferably in the range of 1.8 to 12.8% by weight, more preferably 3 to 10% by weight as the solid content.
If the content of the reinforcing material in the molding composition is small, cracks due to shrinkage may occur during drying after extrusion molding. Even if the content of the reinforcing material in the molded body composition is too large, the reinforcing material may be clogged in the molding die during extrusion molding, which may impair the moldability.

Filler In the present invention, a filler may be contained in the molded body composition. When the filler is included, it is possible to continuously perform extrusion molding and to prepare a molded body excellent in compressive strength and wear resistance.

As the filler, ceramic powder such as cordierite, alumina, zirconia, silicon nitride, silicon carbide, clay mineral can be used.
The content of the filler in the molded body composition is preferably in the range of 0.42 to 12.8% by weight, more preferably 1 to 10% by weight as the solid content.

  If the content of the filler in the molded body composition is low, continuous extrusion moldability is lowered, and it may be difficult to mold a long-sized molded body, particularly a long-sized honeycomb molded body. The mold may be frequently cleaned or replaced, which may reduce productivity and economy. Even if there is too much content of the filler in the composition for shaping | molding bodies, catalyst performance may become inadequate.

Organic additive In this invention, the organic additive may be further contained in the composition for molded objects.
As the organic additive, fatty acid, fatty acid ester and the like are used.
The fatty acid is preferably a saturated fatty acid represented by the following formula (1) and / or an unsaturated fatty acid represented by the following formula (2).
C _n H _2n -CO ₂ H (1)
(Where n is an integer from 4 to 23)
_{C n 'H 2n'-2m +} 1 -CO 2 H ······ (2)
(Where n ′ is an integer from 13 to 23, m is an integer from 1 to 6 representing the number of double bonds)
Specific examples of the saturated fatty acid include stearic acid, lauric acid, myristic acid, behenic acid, arachidic acid, lignoceric acid, palmitic acid and the like, and mixtures thereof.

Examples of unsaturated fatty acids include oleic acid, arachidonic acid, linoleic acid, linolenic acid, icosapentaenoic acid, docosahexaenoic acid, and the like, and mixtures thereof.
In addition, fatty acid esters such as glycerin fatty acid ester, carboxymethyl cellulose, methyl cellulose, hydroxypropyl cellulose, hydroxymethyl cellulose, crystalline cellulose, polyethylene glycol, polypropylene glycol, polyethylene oxide, and the like can also be suitably used.

When such an organic additive is contained, an effect of improving the peelability from the molding die, moldability, and the like can be obtained.
The content of the organic additive in the molding composition is preferably in the range of 0.03 to 4.3% by weight, more preferably 0.5 to 2% by weight.

  If the content of the organic additive in the molded body composition is small, the moldability becomes insufficient, and if it is too much, the pore volume of the resulting molded body catalyst becomes large and the compressive strength becomes insufficient. In some cases, cracks may occur during firing of the molded body.

Active ingredient precursor compound (B)
Furthermore, in this step (i), the active ingredient precursor compound (B) can be mixed.
As the active component precursor compound (B), the same compounds as the active component precursor compound (A) described above can be used.

  The mixing amount of the active component precursor compound (B) is finally obtained in consideration of the content of the active component and the content of the active component precursor compound (A) in the spent titanium oxide-containing exhaust gas treatment catalyst described above. It is preferable that the content of the element as an oxide in the exhaust gas treatment catalyst is 0.001 to 15% by weight, more preferably 0.3 to 12% by weight.

When the content of the active component is small, the NO _x removal rate may be insufficient when used as an exhaust gas treatment catalyst, for example, a selective reduction type NO _x catalyst. Even if there is too much content of an active ingredient, the compressive strength and crack resistance of a molded object will become inadequate.

The composition for solvent molding may contain a solvent in addition to the above components. The solvent is appropriately selected depending on the purpose of use and the molding method.
Specific examples include volatile solvents such as water, methanol, ethanol, propanol, and methyl ethyl ketone, with water being preferred.
The concentration of the solvent in such a molding composition is 15 to 40% by weight, preferably 25 to 35% by weight, and the total solid content is 60 to 85% by weight, more preferably 65 to 75% by weight. It is preferable that it exists in.

If the total solid content concentration of the composition for a molded product is too low, the shape retention of the molded product before drying after the extrusion molding is weak and may be deformed.
Even if the total solid content concentration of the composition for a molded body is too large, the slipping property when passing through the molding die is small, and the moldability, particularly the continuous moldability may be lowered.

Step (j)
The molding composition thus prepared is kneaded and kneaded. The kneading and kneading method is not particularly limited as long as the above materials can be mixed uniformly, and conventionally known mixing methods can be employed.
Usually, a kneader is used, but a continuous kneader, a mixer or the like can also be used.
Kneading and kneading are preferably performed under heating. The temperature at this time is preferably in the range of approximately 80 to 140 ° C, more preferably 90 to 130 ° C. By performing kneading and kneading in such a temperature range, it is possible to prepare a molded article composition having excellent moldability.
Moreover, although mixing time changes also with temperature, it is 0.25 to 5 hours in general.

Step (k)
A kneading and molding method of the kneaded product can use a known molding machine, and can be appropriately selected depending on the shape, type, etc. of the molded body. Usually, an extrusion molding machine is used. When molding a molded body having such a complicated structure, a vacuum extrusion molding machine is preferably used.

Step (l)
The drying method in the drying step (l) is not particularly limited as long as it can be uniformly dried without bending, without causing distortion, and without causing cracks, and a conventionally known method can be employed.
For example, when drying a honeycomb-shaped formed body, the temperature is generally in the range of 30 to 65 ° C., and the drying time is generally in the range of 24 to 72 hours, although it varies depending on the outer diameter, length, pitch, wall thickness, and the like. Preferably there is.

Process (m)
Thereafter, firing is performed, but the firing temperature is preferably in the range of 450 to 700 ° C, more preferably 480 to 600 ° C. If the calcination temperature is low, organic substances such as organic compounds used may remain, which may impair catalyst performance. Even if the calcination temperature is too high, the crystallization of titanium oxide proceeds too much, and the specific surface area and pore volume of the resulting exhaust gas treatment catalyst may become small, and the catalyst performance may be insufficient.
Although the firing time varies depending on the firing temperature, it is generally 1 to 24 hours.
The exhaust gas treatment catalyst according to the present invention can be produced through the above steps.

[Exhaust gas treatment catalyst]
The exhaust gas treatment catalyst according to the present invention is produced by the method described above, and includes (i) a titanium oxide fine powder and (ii) a reinforcing material, and (i) the content of the titanium oxide fine powder is 60 to 97. It is in the range of wt%, and (ii) the content of the reinforcing material is in the range of 3 to 15 wt%.

The content of (i) titanium oxide fine powder in the exhaust gas treatment catalyst of (i) titanium oxide fine powder is in the range of 60 to 97% by weight, preferably 60 to 96% by weight, more preferably 75 to 90% by weight. It is in.
If the content of (i) titanium oxide fine powder in the exhaust gas treatment catalyst is low, the performance of the exhaust gas treatment catalyst, specifically, the NOx removal rate of the selective reduction NOx catalyst may be insufficient.

  If the content of the titanium oxide fine powder (i) in the exhaust gas treatment catalyst is too large, the amount of other reinforcing materials, fillers, and active ingredient precursors described later is limited, so the compression strength of the exhaust gas treatment catalyst, Crack resistance, NOx removal rate, etc. may be insufficient.

  The content of the titanium oxide-based oxide (or component) derived from the spent titanium oxide-containing exhaust gas treatment catalyst in the (i) titanium oxide-based fine powder in the exhaust gas treatment catalyst is 8.5 to 90% by weight, more preferably It is in the range of 10 to 90% by weight, more preferably 25 to 50% by weight. The (i) titanium oxide fine powder also contains other components that have not been removed, such as active ingredients.

(ii) The content of the reinforcing material (ii) in the reinforcing material exhaust gas treatment catalyst is preferably in the range of 3 to 15% by weight, more preferably 3 to 10% by weight.
If the content of the reinforcing material is small, cracks due to shrinkage may occur during drying after extrusion molding, and even if the content of the reinforcing material is too much, the reinforcing material is clogged in the molding die during extrusion molding, It may hinder moldability.

(iii) Active component Furthermore, the exhaust gas treatment catalyst preferably contains the above-mentioned active component as an active component.
The content of the active component in the exhaust gas treatment catalyst is preferably in the range of 0.001 to 15% by weight, more preferably 0.3 to 12% by weight as an oxide. If the content of the active component is small, the NO _x removal rate may be insufficient when used as a selective reduction type NO _x catalyst. Even if there is too much content of an active ingredient, the compressive strength and crack resistance of a molded object will become inadequate.

  Here, the active ingredient is an active ingredient contained in the used exhaust gas treatment catalyst, an activity derived from the active ingredient precursor compounds (A) and (B) used in the step (d) and / or the step (i). It is the sum of ingredients.

The filler exhaust gas treatment catalyst may contain a filler. When it contains a filler, it is excellent in compressive strength and wear resistance.
The exhaust gas treatment catalyst can contain the filler described above.

The filler content in the exhaust gas treatment catalyst is preferably in the range of 0.5 to 15% by weight, more preferably 3 to 10% by weight.
If the content of the filler in the exhaust gas treatment catalyst is small, the strength is low, and even if the content of the filler is too large, the catalyst performance may be insufficient.

As the shape of the exhaust gas treatment catalyst according to the present invention, conventionally known shapes such as pellets, beads, rings, and honeycombs can be adopted.
In the present invention, since the above-described composition for a molded body is used, the moldability is high, and the resulting honeycomb-shaped exhaust gas treatment catalyst is excellent in strength and wear resistance. In addition, by appropriately selecting the type, amount of use, and method of use of the organic additive described above, the moldability is further improved, and a molded product having a reduced thickness and a large number of pitches can be obtained.

The vertical / horizontal size or outer diameter of the honeycomb-shaped exhaust gas treatment catalyst is preferably in the range of 30 to 400 mm.
Here, the external shape of the honeycomb is not particularly limited, such as a quadrangle, a hexagon, a polygon more than an octagon, a circle, and an ellipse, and can be appropriately selected depending on the application and usage.

  If the vertical / horizontal size or the outer diameter of the honeycomb-shaped exhaust gas treatment catalyst is less than 30 mm, when used as a selective reduction-type NOx catalyst of the honeycomb-shaped exhaust gas treatment catalyst, the number of production increases, which is not economical. When the vertical / horizontal size or the outer diameter of the honeycomb-shaped exhaust gas treatment catalyst exceeds 400 mm, there is no extrusion molding apparatus capable of molding a honeycomb-shaped exhaust gas treatment catalyst of this size.

The length of the honeycomb-shaped exhaust gas treatment catalyst is preferably in the range of 3 to 1500 mm, more preferably 50 to 1300 mm.
When the length of the honeycomb-shaped exhaust gas treatment catalyst is less than 3 mm, it is difficult to manufacture.
When the length of the honeycomb-shaped exhaust gas treatment catalyst exceeds 1500 mm, there are few uses.
The pitch of the honeycomb-shaped exhaust gas treatment catalyst is preferably in the range of 6 to 500 cpsi, more preferably 15 to 200 cpsi.

When the pitch of the honeycomb-shaped exhaust gas treatment catalyst is less than 6 cpsi, the opening is large and the shape retaining property is weakened, which makes it difficult to manufacture.
If the pitch of the honeycomb-shaped exhaust gas treatment catalyst exceeds 500 cpsi, pressure loss may increase at the time of molding, and molding may become difficult.

The thickness of the honeycomb-shaped exhaust gas treatment catalyst is preferably in the range of 0.1 to 1.9 mm, more preferably 0.1 to 1.5 mm.
It is difficult to obtain a honeycomb-shaped exhaust gas treatment catalyst having a thickness of less than 0.1 mm.
When the thickness of the honeycomb-shaped exhaust gas treatment catalyst exceeds 1.9 mm, the ratio of the effective surface of the honeycomb that contributes to the catalyst performance decreases, and sufficient performance may not be obtained.

[Example]
Hereinafter, although an example explains, the present invention is not limited by these examples.
[Example 1]
Preparation of exhaust gas treatment catalyst (1) Used titanium oxide-containing exhaust gas treatment catalyst (honeycomb shape: honeycomb hole number 20 × 20, length 1000 mm, composition: TiO ₂ = 79.65 wt%, WO ₃ = 8.0 weight %, V ₂ O ₅ = 0.90 wt%, Impurity: Na ₂ O = 0.35 wt%, K ₂ O = 0.30 wt%, CaO = 1.5 wt%, SO ₄ = 6.13 % By weight) was pulverized with a pulverizer (Yariya Machine Seisakusho: Yariya pulverizer).
Next, the pulverized used titanium oxide-containing exhaust gas treatment catalyst was sieved with a sieve (mesh size = 0.5 mm (Japanese Industrial Standard (JIS) regulations)) to obtain a used catalyst pulverized product (1). Step (a)

The average particle size of the used catalyst ground product (1) was measured, and the results are shown in the table.
37.5 kg of metatitanic acid slurry (manufactured by Ishihara Sangyo Co., Ltd .: MT-A, TiO ₂ concentration 30 wt%, pH 1.18) was charged into a stirring tank equipped with a heating reflux, and 17.4 kg of used catalyst pulverized product (1) And stirred at 30 ° C. for 6 hours to obtain a mixed slurry. Step (b)
The pH of the mixed slurry after cooling was 1.42.
Subsequently, the mixed slurry was filtered with a vacuum filter and dehydrated. Step (c)

The filtrate was analyzed for Na ₂ O, K ₂ O, CaO, and V ₂ O _5, and the removal rate from the used catalyst ground product (1) is shown in the table.
After adding 1.42 kg of ammonium paratungstate (manufactured by Nippon Shin Metal Co., Ltd.) to 48.4 kg of the filtered and dehydrated cake (solid content concentration 51.7 wt%), ammonia water having a concentration of 15 wt% 20 kg was added to neutralize. At this time, the pH of the neutralized slurry was 9.5. Next, the mixture was aged with stirring at 95 ° C. for 3 hours. Step (d)

Thereafter, this neutralized / ripened slurry was cooled to 40 ° C., then filtered, and sprayed to prepare a washed cake having a solid content concentration of 49% by weight. Step (e)

The washed cake was dried at 110 ° C. for 20 hours, and further calcined at 550 ° C. for 5 hours, and then pulverized by a pulverizer (Yariya Machinery Co., Ltd .: Yarya pulverizer), and a titanium oxide fine powder containing a used catalyst. (1) was obtained. Step (f), Step (g), Step (h)

The composition of the resulting titanium oxide fine powder (1) was analyzed, the average particle size was measured, and the results are shown in the table.
A solution of 0.082 kg of ammonium metavanadate dissolved in 0.250 kg of monoethanolamine and 3.5 kg of water were added to 24.1 kg of titanium oxide fine powder (1), and then ammonia water was added to the mixed slurry. The pH was adjusted to 7.9, and the mixture was kneaded for 0.5 hours while heating to 120 ° C. with a kneader.

Thereafter, 1.39 kg of glass fiber (hereinafter sometimes referred to as “GF”) as a reinforcing material, 0.26 kg of acidic clay as a filler, and 0.500 kg of polyethylene oxide as an organic additive are added to the mixed slurry. Furthermore, it was kneaded at 60 ° C. for 3 hours with a kneader to prepare a molding composition (1). Step (i), Step (j)

The content (usage standard) of each component in the molded article composition (1) is shown in the table. The moisture content was measured with an infrared moisture meter (Ketto Kagaku Kenkyusho: FD-610).
The molded body composition (1) is extruded with a vacuum extrusion molding machine (Miyazaki Tekko Co., Ltd.), and the outer diameter is 75 mm on one side of the plane, about 500 mm in the penetration direction, and the aperture (Rectangular through hole diameter) A honeycomb structure (1) having a diameter of 6.4 mm, a partition wall thickness of 1.0 mm, and an aperture ratio of 72% was obtained. Step (k)

Next, the obtained honeycomb structure (1) was dried at 60 ° C. for 48 hours and then fired at 600 ° C. for 3 hours to prepare a honeycomb-shaped exhaust gas treatment catalyst (1). Step (l), Step (m)

The dimensions of the honeycomb-shaped exhaust gas treatment catalyst (1) were measured, and the results are shown in the table. In addition, the contents (usage standard) of each component in the honeycomb-shaped exhaust gas treatment catalyst (1) are shown in the table.
Further, the specific surface area, pore volume, compressive strength, wear strength and denitration catalyst performance of the honeycomb-shaped exhaust gas treatment catalyst (1) were measured by the following methods, and the results are shown in the table.

<Specific surface area>
The specific surface area of the honeycomb-shaped exhaust gas treatment catalyst (1) is determined by a specific surface area measuring device based on the BET method using a mixed gas of 30% nitrogen and 70% helium as an adsorbed gas.
<Pore volume>
The total pore volume of the honeycomb-shaped exhaust gas treatment catalyst (1) is obtained by a mercury intrusion method.
(Reference measurement method: The measurement method of pore volume was measured with a mercury intrusion method pore distribution measuring device (manufactured by QANTA CROME: PM-33GT1LP) (pressure range: 32 to 32200 psi).

<Compressive strength>
Using a compressive strength machine (manufactured by Tokyo Test Machine Co., Ltd .: Model AL / B30P), the honeycomb exhaust gas treatment catalyst (1) is cut into a cube or a rectangular parallelepiped, and the honeycomb hole penetration direction and the direction perpendicular to this direction A compression load is applied at a constant speed (hereinafter also simply referred to as “orthogonal direction”), the maximum load (N) until the sample is broken is read, and the compression strength is obtained from the following equation (4).
Compressive strength (N / cm ² ) = W (N) / {a (cm) × c (cm)} (4)
Here, a (cm) and c (cm) indicate the dimensions of the two sides of the pressing surface of the sample. W (N) indicates the maximum load until the sample is completely destroyed by applying a load gradually.

<Abrasion strength>
A honeycomb-shaped exhaust gas treatment catalyst (1) with 9 × 9 honeycomb holes and a length of 100 mm in the penetrating direction (the other dimensions are cut out and adjusted) is used as a test sample, and this test sample is filled into a flow reactor. did. A gas containing sand was passed through the flow reactor under the following conditions, and the wear rate was measured based on the following equation (5) from the amount of decrease in the catalyst weight. The amount of sand passing through the flow reactor was determined by providing a cyclone in the rear stage of the flow reactor, and measuring the weight of the sand collected in the cyclone after the wear test.

Test conditions Catalyst shape: Honeycomb hole number 9x9, length 100mm
Gas flow rate: (16.5 ± 2) m / s (catalyst cross section)
Gas temperature: Room temperature 25 ° C
Gas distribution time: 3 hours Sand concentration: (40 ± 5) g / Nm ³
Sand: Silica sand Average particle size 500μm
Abrasion rate (% / kg) = {[catalyst weight before starting wear test (g) −catalyst weight after finishing wear test (g)] / catalyst weight before starting wear test (g)} × 100 / sand passing amount (Kg) (5)

<Denitration catalyst performance test>
The honeycomb-shaped exhaust gas treatment catalyst (1) is a honeycomb-shaped exhaust gas treatment catalyst (1) comprising a honeycomb structure having a honeycomb hole number of 3 × 3 and a length of 300 mm in the penetration direction (the other dimensions are cut out and adjusted) Was used as a test sample, and this test sample was charged into a flow reactor. A model gas having the following composition was passed through the flow reactor to measure the denitration rate. The denitration rate of nitrogen oxides (NO _x ) in the gas before and after contact with the catalyst was determined by the following equation (6). At this time, the concentration of NO _x was measured with a chemiluminescent nitrogen oxide analyzer (manufactured by Anatech Yanaco: ECL-88AO).
Denitration rate (%) = {[NO _{x in} non-contact gas (ppm by mass) −NO _x in gas after contact (mass ppm)] / NO _{x in} non-contact gas (mass ppm)} × 100・ (6)

Test conditions Catalyst shape: Honeycomb hole number 3x3, length 300mm
Reaction temperature: 380 ° C., superficial velocity (SV) = 20,000 hr ⁻¹
Model gas composition: NO _x = 180 mass ppm, NH ₃ = 180 mass ppm, SO ₂ = 500
Mass ppm, O ₂ = 2 wt%, H ₂ O = 10 wt%, N ₂ = balance

[Example 2]
Preparation of exhaust gas treatment catalyst (2) Used titanium oxide-containing exhaust gas treatment catalyst pulverized in the same manner as in Example 1 is sieved with a sieve (mesh size = 0.3 mm (Japanese Industrial Standard (JIS) regulations)) and used. A finished catalyst pulverized product (2) was obtained. Step (a)

The average particle size of the used catalyst ground product (2) was measured, and the results are shown in the table.
Thereafter, a honeycomb-shaped exhaust gas treatment catalyst (2) was prepared in the same manner except that the used catalyst ground product (2) was used.
Each dimension of the honeycomb-shaped exhaust gas treatment catalyst (2) was measured, and the results are shown in the table. Further, the contents (usage standard) of each component in the honeycomb-shaped exhaust gas treatment catalyst (2) are shown in the table.
Further, the specific surface area, pore volume, compressive strength, wear strength and denitration catalyst performance of the honeycomb-shaped exhaust gas treatment catalyst (2) were measured by the following methods, and the results are shown in the table.

[Example 3]
Preparation of exhaust gas treatment catalyst (3) Used titanium oxide-containing exhaust gas treatment catalyst pulverized in the same manner as in Example 1 is sieved with a sieve (mesh size = 0.7 mm (Japanese Industrial Standard (JIS) regulations)) and used. A finished catalyst pulverized product (3) was obtained. Step (a)

The average particle size of the used catalyst ground product (3) was measured, and the results are shown in the table.
Thereafter, a honeycomb-shaped exhaust gas treatment catalyst (3) was prepared in the same manner except that the used catalyst ground product (3) was used.
Each dimension of the honeycomb-shaped exhaust gas treatment catalyst (3) was measured, and the results are shown in the table. Further, the content (usage standard) of each component in the honeycomb-shaped exhaust gas treatment catalyst (3) is shown in the table.
Further, the specific surface area, pore volume, compressive strength, wear strength and denitration catalyst performance of the honeycomb-shaped exhaust gas treatment catalyst (3) were measured by the following methods, and the results are shown in the table.

[Example 4]
Preparation of exhaust gas treatment catalyst (4) In step (b) of Example 1, 7.5 kg of metatitanic acid slurry (manufactured by Ishihara Sangyo Co., Ltd .: MT-A, TiO ₂ concentration 30 wt%) was charged and used catalyst pulverized. Product (1) A mixed slurry was prepared in the same manner except that 31.3 kg was added . Step (b)
Subsequently, the mixed slurry was filtered with a vacuum filter and dehydrated. Step (c)

The filtrate is analyzed for Na ₂ O, K ₂ O, CaO, and V ₂ O _5, and the amount and rate of desorption (elution) from the used catalyst pulverized product (1) are shown in the table.
Next, after adding 0.32 kg of ammonium paratungstate (manufactured by Nippon Shin Metal Co., Ltd.) to 48.3 kg of the filtered and dehydrated cake (solid content concentration 51.8 wt%), the concentration was 15 wt%. 18 kg of aqueous ammonia was added for neutralization. At this time, the pH of the neutralized slurry was 9.53. Next, the mixture was aged with stirring at 95 ° C. for 3 hours. Step (d)

Thereafter, a honeycomb-shaped exhaust gas treatment catalyst (4) was prepared in the same manner as in Example 1.
The dimensions of the honeycomb-shaped exhaust gas treatment catalyst (4) were measured, and the results are shown in the table. Further, the contents (usage standard) of each component in the honeycomb-shaped exhaust gas treatment catalyst (4) are shown in the table.
Further, the specific surface area, pore volume, compressive strength, wear strength and denitration catalyst performance of the honeycomb-shaped exhaust gas treatment catalyst (4) were measured by the following methods, and the results are shown in the table.

[Example 5]
Preparation of Exhaust Gas Treatment Catalyst (5) In step (b) of Example 1, 67.5 kg of metatitanic acid slurry (manufactured by Ishihara Sangyo Co., Ltd .: MT-A, TiO ₂ concentration 30% by weight) was charged and used catalyst pulverized. Product (1) A mixed slurry was prepared in the same manner except that 3.48 kg was added. Step (b)
Subsequently, the mixed slurry was filtered with a vacuum filter and dehydrated. Step (c)

The filtrate is analyzed for Na ₂ O, K ₂ O, CaO, and V ₂ O _5, and the amount and rate of desorption (elution) from the used catalyst pulverized product (1) are shown in the table.
Next, after adding 2.52 kg of ammonium paratungstate (manufactured by Nippon Shin Metal Co., Ltd.) to 49.5 kg of the filtered and dehydrated cake (solid content concentration 50.5 wt%), the concentration was 15 wt%. It neutralized by adding 28 kg of aqueous ammonia. At this time, the pH of the neutralized slurry was 9.5. Next, the mixture was aged with stirring at 95 ° C. for 3 hours. Step (d)

Thereafter, a honeycomb-shaped exhaust gas treatment catalyst (5) was prepared in the same manner as in Example 1.
Each dimension of the honeycomb-shaped exhaust gas treatment catalyst (5) was measured, and the results are shown in the table. Further, the content (usage standard) of each component in the honeycomb-shaped exhaust gas treatment catalyst (5) is shown in the table.
Further, the specific surface area, pore volume, compressive strength, wear strength and denitration catalyst performance of the honeycomb-shaped exhaust gas treatment catalyst (5) were measured by the following methods, and the results are shown in the table.

[Example 6]
Preparation of exhaust gas treatment catalyst (6) In step (d) of Example 1, 18 kg of ammonia water having a concentration of 15% by weight was added without adding 1.42 kg of ammonium paratungstate (manufactured by Nippon Shin Metal Co., Ltd.). Neutralized. At this time, the pH of the neutralized slurry was 9.55. Next, the mixture was aged with stirring at 95 ° C. for 3 hours. Step (d)

Thereafter, a honeycomb-shaped exhaust gas treatment catalyst (6) was prepared in the same manner as in Example 1.
Each dimension of the honeycomb-shaped exhaust gas treatment catalyst (6) was measured, and the results are shown in the table. Further, the content (usage standard) of each component in the honeycomb-shaped exhaust gas treatment catalyst (6) is shown in the table.
Further, the specific surface area, pore volume, compressive strength, wear strength and denitration catalyst performance of the honeycomb-shaped exhaust gas treatment catalyst (6) were measured by the following methods, and the results are shown in the table.

[Example 7]
Preparation of exhaust gas treatment catalyst (7) In step (b) of Example 1, 37.5 kg of titanyl sulfate (manufactured by Teika Co., Ltd .: TM crystal, TiO ₂ concentration 30% by weight) was used instead of metatitanic acid slurry. Was similarly mixed slurry. Step (b)

The pH of the mixed slurry after cooling was 9.54.
Thereafter, a honeycomb-shaped exhaust gas treatment catalyst (7) was prepared in the same manner as in Example 1.
Each dimension of the honeycomb-shaped exhaust gas treatment catalyst (7) was measured, and the results are shown in the table. Further, the content (usage standard) of each component in the honeycomb-shaped exhaust gas treatment catalyst (7) is shown in the table.
Further, the specific surface area, pore volume, compressive strength, wear strength and denitration catalyst performance of the honeycomb-shaped exhaust gas treatment catalyst (7) were measured by the following methods, and the results are shown in the table.

[Comparative Example 1]
Preparation of exhaust gas treatment catalyst (R1) 75.0 kg of metatitanic acid slurry (manufactured by Ishihara Sangyo Co., Ltd.) was charged into a stirring tank equipped with a heating reflux, and 2.79 kg of ammonium paratungstate was added and mixed. The pH was adjusted to 9.5 by adding 23 kg of aqueous ammonia by weight, and aged with stirring at 95 ° C. for 1 hour. Then, this mixed slurry was cooled to 40 ° C., then filtered, and washed with water to prepare a washed cake having a solid content concentration (TiO ₂ · WO ₃ ) of 49% by weight.

Next, the washed cake was dried at 110 ° C. for 20 hours, further calcined at 550 ° C. for 5 hours, and then pulverized by a pulverizer (Yariya Machinery Co., Ltd .: Yarya pulverizer). A powder (R1) was obtained. Step (f), Step (g), Step (h)

  The composition of the obtained titanium oxide fine powder (R1) was analyzed, the average particle size was measured, and the results are shown in the table. Next, a solution obtained by dissolving 0.273 kg of ammonium metavanadate in 0.250 kg of monoethanolamine and 3.5 kg of water were added to 24.0 kg of titanium oxide fine powder (1), and then ammonia water was added and mixed. The slurry was adjusted to pH 7.8 and kneaded for 0.5 hours while heating to 120 ° C. with a kneader.

Thereafter, 1.39 kg of glass fiber (hereinafter sometimes referred to as “GF”) as a reinforcing material, 0.26 kg of acidic clay as a filler, and 0.500 kg of polyethylene oxide as an organic additive are added to the mixed slurry. Furthermore, it was kneaded at 60 ° C. for 3 hours with a kneader to prepare a molding composition (R1). Step (i), Step (j)

Thereafter, a honeycomb-shaped exhaust gas treatment catalyst (R1) was prepared in the same manner as in Example 1.
Each dimension of the honeycomb-shaped exhaust gas treatment catalyst (R1) was measured, and the results are shown in the table. Further, the contents (usage standard) of each component in the honeycomb-shaped exhaust gas treatment catalyst (R1) are shown in the table.
Further, the specific surface area, pore volume, compressive strength, wear strength and denitration catalyst performance of the honeycomb-shaped exhaust gas treatment catalyst (R1) were measured by the following methods, and the results are shown in the table.

[Comparative Example 2]
Preparation of exhaust gas treatment catalyst (R2) Used titanium oxide-containing exhaust gas treatment catalyst pulverized in the same manner as in Example 1 is sieved with a sieve (mesh size = 1.0 mm (Japanese Industrial Standard (JIS) regulations)) and used Used catalyst pulverized product (R2) was obtained. Step (a)

The average particle size of the used catalyst ground product (R2) was measured, and the results are shown in the table.
Thereafter, a honeycomb-shaped exhaust gas treatment catalyst (R2) was prepared in the same manner except that the used catalyst ground product (R2) was used.
Each dimension of the honeycomb-shaped exhaust gas treatment catalyst (R2) was measured, and the results are shown in the table. In addition, the content (usage standard) of each component in the honeycomb-shaped exhaust gas treatment catalyst (R2) is shown in the table.
Further, the specific surface area, pore volume, compressive strength, wear strength and denitration catalyst performance of the honeycomb-shaped exhaust gas treatment catalyst (R2) were measured by the following methods, and the results are shown in the table.

[Comparative Example 3]
Preparation of exhaust gas treatment catalyst (R3) In step (b) of Example 1, 0.4 kg of metatitanic acid slurry (manufactured by Ishihara Sangyo Co., Ltd .: MT-A, TiO ₂ concentration 30% by weight) was charged and used catalyst pulverized. Product (1) A mixed slurry was prepared in the same manner except that 34.7 kg was added. Step (b)
Subsequently, the mixed slurry was filtered with a vacuum filter and dehydrated. Step (c)

The filtrate is analyzed for Na ₂ O, K ₂ O, CaO, and V ₂ O _5, and the amount and rate of desorption (elution) from the used catalyst pulverized product (1) are shown in the table.
Next, 0.06 kg of ammonium paratungstate (manufactured by Nippon Shin Metal Co., Ltd.) was added to 48.1 kg of the filtered / dehydrated cake (solid concentration 52.0 wt%) and mixed. 16 kg of aqueous ammonia was added for neutralization. At this time, the pH of the neutralized slurry was 9.52. Next, the mixture was aged with stirring at 95 ° C. for 3 hours. Step (d)

Thereafter, a honeycomb-shaped exhaust gas treatment catalyst (R3) was prepared in the same manner as in Example 1.
Each dimension of the honeycomb-shaped exhaust gas treatment catalyst (R3) was measured, and the results are shown in the table. Further, the content (usage standard) of each component in the honeycomb-shaped exhaust gas treatment catalyst (R3) is shown in the table.
Further, the specific surface area, pore volume, compressive strength, wear strength and denitration catalyst performance of the honeycomb-shaped exhaust gas treatment catalyst (R3) were measured by the following methods, and the results are shown in the table.

[Comparative Example 4]
Preparation of exhaust gas treatment catalyst (R4) In step (b) of Example 1, 69.0 kg of metatitanic acid slurry (manufactured by Ishihara Sangyo Co., Ltd .: MT-A, TiO ₂ concentration 30 wt%) was charged and used catalyst pulverization Product (1) A mixed slurry was prepared in the same manner except that 2.79 kg was added. Step (b)
Subsequently, the mixed slurry was filtered with a vacuum filter and dehydrated. Step (c)

The filtrate is analyzed for Na ₂ O, K ₂ O, CaO, and V ₂ O _5, and the amount and rate of desorption (elution) from the used catalyst pulverized product (1) are shown in the table.
Next, after adding 0.06 kg of ammonium paratungstate (manufactured by Nippon Shin Metal Co., Ltd.) to 49.0 kg of the filtered / dehydrated cake (solid content concentration 51.0 wt%), the concentration was 15 wt%. 16 kg of aqueous ammonia was added for neutralization. At this time, the pH of the neutralized slurry was 9.54. Next, the mixture was aged with stirring at 95 ° C. for 3 hours. Step (d)

Thereafter, a honeycomb-shaped exhaust gas treatment catalyst (R4) was prepared in the same manner as in Example 1.
Each dimension of the honeycomb-shaped exhaust gas treatment catalyst (R4) was measured, and the results are shown in the table. In addition, the contents (usage standard) of each component in the honeycomb-shaped exhaust gas treatment catalyst (R4) are shown in the table.
Further, the specific surface area, pore volume, compressive strength, wear strength and denitration catalyst performance of the honeycomb-shaped exhaust gas treatment catalyst (R4) were measured by the following methods, and the results are shown in the table.

[Comparative Example 5]
Preparation of exhaust gas treatment catalyst (R5) Used titanium oxide-containing exhaust gas treatment catalyst (honeycomb shape: honeycomb hole number 20 × 20, length 1000 mm, composition: TiO ₂ = 79.65% by weight, WO ₃ = 8.0% by weight %, V ₂ O ₅ = 0.90 wt%, Impurity: Na ₂ O = 0.35 wt%, K ₂ O = 0.30 wt%, CaO = 1.5 wt%, SO ₄ = 6.13 % By weight) was used as a honeycomb-shaped exhaust gas treatment catalyst (R5).
The specific surface area, pore volume, compressive strength, and wear strength of the honeycomb-shaped exhaust gas treatment catalyst (R5) were measured, and the results are shown in the table.
The honeycomb-shaped exhaust gas treatment catalyst (R5) was cut out and adjusted to have a honeycomb hole number of 3 × 3 and a length of 300 mm in the penetration direction, and the denitration catalyst performance was measured in the same manner as in Example 1. The results are shown in the table.

その他成分は、主に(WO₃, Al₂O₃, SiO₂)である。

The other components are mainly (WO ₃ , Al ₂ O ₃ , SiO ₂ ).

Claims (6)

A powder preparation step of pulverizing a used titanium oxide-containing exhaust gas treatment catalyst to obtain a powder having an average particle size of 0.1 to 15 μm;
A mixing step of obtaining a mixed slurry by mixing at least one of an aqueous titanyl sulfate solution and a metatitanic acid slurry and the powder;
A filtration step of filtering the mixed slurry to obtain a cake;
The cake and the basic compound are mixed and neutralized to obtain a titanium oxide gel,
After firing the titanium oxide gel, pulverizing to obtain a titanium oxide fine powder;
A method for producing a fine titanium oxide powder, comprising: In the mixing step, the total TiO of the titanyl sulfate aqueous solution and the metatitanic acid slurry in the mixed slurry. ₂ Concentration (C _T ) And solid content concentration of powder in the mixed slurry (C _RC ) (C) _T / C _RC ) Is mixed so as to be 0.1 to 9.0. The method for producing a fine titanium oxide powder according to claim 1. The method for producing a titanium oxide fine powder according to claim 1 or 2, wherein the titanium oxide gel obtained in the neutralization step has a pH of 7 to 12. The production of the titanium oxide fine powder according to any one of claims 1 to 3, further comprising a step of mixing the cake and the active ingredient precursor compound between the filtration step and the neutralization step. Method. The active component precursor compound is a compound containing at least one element selected from V, W, Mo, Cr, Mn, Fe, Ni, Cu, Ag, Au, Pd, Y, Ce, Nd, In, and Ir. The method for producing a fine titanium oxide powder according to claim 4. A method for producing an exhaust gas treatment catalyst, comprising: a step of mixing the titanium oxide fine powder obtained by the production method according to claim 1 and a reinforcing material; and a step of molding.